1. Field of the Invention
The present invention relates generally to a lens assembly and an eccentricity adjustment apparatus thereof, and more particularly to a lens assembly provided with a means for adjusting a resolution level in the process of assembling lenses into the lens assembly, and an apparatus for improving a resolution by rotating a specific lens of the lens assembly on the optical axis.
2. Description of Related Art
Generally, in the process of assembling a lens assembly for use in a TV camera or the like, lenses are fitted into a lens barrel, and then a collimator is attached to the end of the lens assembly. The lens assembly is adjusted to increase a resolution level (e.g., Modulation Transfer Function (MTF)) while the image quality of the lens assembly is observed through a microscope.
Conventionally, a front lens is detached and a press ring of a lens that is a subject of the adjustment is loosened and the lens is rotated on the optical axis for adjusting the position of the lens. Alternatively, a unit holding the lens is rotated in order to adjust the position of the lens. These methods, however, require a long period since the lens assembly cannot be adjusted while the image quality of the lens assembly is observed.
In another conventional method, a specific lens of a lens assembly is, supported in such a manner as to move vertically and horizontally within a plane perpendicular to the optical axis, and the lens is moved within the plane by means of screws, which are inserted along the diameter of a lens frame. In addition, Japanese Patent Provisional Publication No. 62-295011 discloses a method of adjusting the optical axis of the lens by means of a special jig before the lenses are fitted into the lens barrel. In these methods, the screws are inserted along the diameter of the lens frame, and thus, the lens frame must be thick and large in diameter.
In view of the foregoing, it is an object of the present invention to provide a lens assembly and an eccentricity adjustment apparatus thereof, which make it possible to easily adjust a lens while the image quality of the lens assembly is observed and also reduces the number of assembly processes.
To achieve the above-mentioned object, the present invention is directed to a lens barrel comprising: a lens; and a tilting mechanism for supporting the lens tiltably with respect to an optical axis; wherein the tilting mechanism adjusts a tilt angel of the lens from the outside of the lens barrel.
According to the present invention, a specific lens, which has a great effect on the resolution with respect to a slight displacement, is selected from the lens optical system and is supported by the tilting mechanism. The tilting mechanism enables the tilt angle of the lens to be adjusted from outside of the lens barrel. After the lenses are fitted into the lens barrel, the lens assembly can be adjusted to achieve a desired lens performance while the image quality of the lens assembly is observed. This reduces the number of assembly processes and makes the lens performance uniform. In addition, there is no necessity of disassembling the lens assembly for the adjustment, and the readjustment can be performed easily.
For example, the tilting mechanism is constructed in such a manner that: the lens is arranged in a cylindrical member; a reference member and a plurality of eccentric members for supporting the lens from the outside are provided on the circumference of the cylindrical member; and connecting parts for connecting to the reference member and the eccentric members are formed at the outer circumference of the lens, the tilting mechanism being able to adjust the tilt angel of the lens by moving the eccentric members. The lens may be fitted in the lens frame, or the lens frame may be integrated with the lens.
To achieve the above-mentioned object, the present invention is directed to a lens barrel, comprising: a lens supported rotatably about an optical axis; an opening formed at the circumference of the lens barrel; and a power transmission mechanism for transmitting a force, applied from the outside of the lens barrel, to the lens through the opening to thereby adjust an eccentricity of the lens.
More specifically, the opening is formed at the circumference of the lens barrel, and the force is transmitted from outside of the lens barrel to the lens within the lens barrel through the power transmission mechanism to thereby rotate the lens about the optical axis and adjust the eccentricity thereof. The lens may be fitted in the lens frame, or the lens frame may be integrated with the lens.
According to the present invention, the lens, which is a subject of the adjustment, can be rotated from outside the lens barrel without detaching the lens from the lens barrel. Therefore, the lens can be adjusted to achieve a desired lens performance while the image quality of the lens assembly is observed.
The lens barrel according to the present invention may employ, for example, the eccentricity adjustment apparatus comprising: a supporting base attached to the circumference of the lens barrel; a rotary member rotatable supported on the supporting base; and a power transmission mechanism for transmitting a rotational force of the rotary member to the lens through the opening of the lens barrel, and rotating the lens in accordance with the rotated mount of the rotary member.
According to the present invention, the supporting base is attached to the circumference of the lens barrel with the lens being fitted in the lens barrel. The rotary member is pivotally supported on the supporting base, and the opening is formed in the lens barrel so that the rotational force of the rotary member can be transmitted to the inside of the lens barrel. The power transmission mechanism transmits the rotational force of the rotary member to the lens, which rotates about the optical axis.
Alternatively, the lens barrel may be characterized in that: the opening is formed along the circumference of the lens barrel; at least one connecting part is formed on the circumference of the lens; a control member is connected to and disconnected from the lens in such a manner that the control member is inserted into and extracted from the connecting part through the opening; and the eccentricity of the lens is adjusted by moving the control member connected to the connecting part along the opening.